Up to now, as an angular velocity sensor including a vibrating member, an angular velocity sensor in which the vibrating member includes first and second drive pieces and a detection piece has been proposed (for example, refer to Patent Literature 1). In this kind of angular velocity sensor, the first and second drive pieces and the detection piece are fixed to a base portion.
Specifically, the vibrating member of the angular velocity sensor is of a so-called tripod tuning fork type which is formed by etching a substrate made of a piezoelectric material. Further, the vibrating member has the first and second drive pieces and the detection piece, and the first and second drive pieces and the detection piece are projected from the base portion in the same direction.
The detection piece is disposed between the first and second drive pieces. Each of the first and second drive pieces and the detection piece has a rectangular cross-sectional shape having side surfaces perpendicular to an array direction of the first and second drive pieces and the detection piece, and a front surface and a rear surface perpendicular to the side surfaces (in parallel to a plane direction of the substrate).
In the above-described angular velocity sensor, when pulsed drive signals different in phase by 180° are supplied to the respective first and second drive pieces, the first and second drive pieces vibrate in the array direction of the first and second drive pieces and the detection piece, and the detection piece maintains a substantially stationary state. When an angular velocity is applied in this state, a pair of Coriolis forces whose directions are opposite to each other along a projecting direction are generated in the first and second drive pieces, and moments generated by the Coriolis forces are transmitted to the detection piece through the base portion. As a result, the detection piece vibrates (is bent) according to the angular velocity, and the angular velocity is detected on the basis of charge generated on the detection piece.
In the above-described angular velocity sensor, although the cross-section surface of each of the first and second drive pieces has the rectangular shape, it is difficult to make the side surfaces completely perpendicular to the front surface and the rear surface at respective connection portions, and the connection portions are slightly rounded (have tapered shapes). For this reason, when the first and second drive pieces are vibrated, the first and second drive pieces may be displaced (unnecessarily vibrated) in a normal direction (a direction perpendicular to a vibration direction) to the plane direction of the substrate. When the first and second drive pieces are displaced in the normal direction, the moments caused by the displacement are transmitted to the detection piece, thereby adversely affecting a detection precision.